Need to Know
by Everybutnone
Summary: Is his first time in a solo undercover mission since they have been together and he only wants to impress her, but everything is not as it should be. There's always a story and he's not going to stop until he gets to be bottom of it. AU Established Caskett. First fic, ever!
1. Need to know

**Disclaimer: **I own it. I make millions of this show. I live in the beach in Costa Rica, and I never have to work a single day of my life...

But is not really mine, I don't have money, I live in Costa Rica but it takes more than an hour to get to the beach and enjoy, maybe.

* * *

**Prologue.**

He walk trough the door. He was really nervous but no one could know it, he had to act as though everything was fine. "Just peachy!" was his sarcastic motto.

He had to get to back room. It wasn't that difficult, except for the guards that were in the hall. He toke a deep breath. "I can do this" he thought "I have to impress _her_"

He nodded his head to the guards as he pass by. Now came the real hard part, getting one of the girls that _works_ there to talk about what was really happening behind those close doors.

"It's going to be easy" he tried to lied to himself.

The back room was open, the only things that you could see there were doors and young girls, some look not older than 16 others look close to 25 but still pretty enough. One of the older ones was looking at him, no she wasn't looking, she was _studying_ him, and she wasn't the only one.

* * *

She saw him as soon as he walk in. He was wearing expensive designer clothes. Of course she knew who he was; she has been reading his books since she could remember. She also could guess why he was there, it was because of _her_.

He looks like he didn't wanted to be there, and she saw that the guards were noticing this. It was time to make her move.

* * *

He could feels eyes in his back; he didn't know what to do or how to act. He could feel himself starting to shake. He was so lost in his brain that he didn't realize that the girl that was looking at him, was now right in front of him.

He felt someone touching his back, and he could hear someone talking but he couldn't make sense of the worlds that were been spoken. When he felt a breath on his ear, he came out of his head.

"You have to trust me, Writer Boy", she said.

He couldn't understand why, but he felt safe. He didn't know how she recognized him, but he couldn't care less. Right now she was his best shot. But he still didn't know what he should be doing.

"Follow my lead" she said, like she was reading his mind.

Before he knew what was going on, she grabbed his hand and led him to a door among the dozens that made the walls of the back room.

"Take your shirt of" she tall him as soon as the door close behind him. When he didn't respond right away she begins to do it herself. "We don't have much time" she said as she toke off his shirt, "they are going to be here soon enough, and we have to take that mic, before they search you"

He didn't act, he just let her do what she had to do. He was paralized.

All the sudden she stopped and asked "Do you have audio?" He couldn't speak, so he just nodded his head. Next thing he knew, she was talking straight to the mic.

"Kiss me, Kate" was what she said. He couldn't understand what that meant but he heard a voice in his ear, it was _her _voice. "Castle, say 'bye, bye birdie', and do it quick", and he did. As soon as that phrase left his lips, this girl was taking his mic and earplug off, and throwing them behind the headboard of the bed.

When she finished doing that, she toke of her shirt and grabbed his hips to pull him flush with her. And just in time, because at that exact moment the door open and a couple of guards came in.

"Boys, is everything ok?" He couldn't understand how she was so calm.

"We have to search him" said one of the guards.

In that moment he found his voice. "Be my guest!" It was the only thing he could say. And so they did. As this happen, he also realized that as he was being search by one guard the other one was looking as her.

When they were finishing he heard that new voice again. "Anything amiss, boys?" she ask with a smirk on her face. They just glared at her and toss the door as they walk out.

A soon as they walk out the door she explained the plan to him. She never tall him who she was and although he wanted to ask he didn't think it was the right time, but he was definitely going to find out.

* * *

**AN: **Well this is my first fic.

English is NOT my first language, so I'm sorry if something is off (Please let me know if it is!)

I think this is a multi-chapter fic, but i'm not going to write more, on less someone is reading, so please review and let me know if you think I should continue to write.

BTW, I'm a college student, so chapters are NOT gonna have a schedule.

Hope you enjoy it.


	2. And so, it begins!

**AN:** I guess the only I can say is Thank You to all of you who read, above all to those who choose to follow this story.

Also I frogot to mention that I don't own the names of the musicals in the first installment of this fic.

I guess here goes nothing.

* * *

**Chapter 1: And so, it begins**

It was a simple plan, his only job was to walk out and touch his nose. Every girl knew that this was the sign for the cops being in their way, and that they needed to hide until The Boss was found. She never told him how they all knew it. He _really _wanted to ask but she didn't let him.

When he got out of the complex, he went straight to the van, straight to _her_. Once he got there, they moved the van to the parking lot next door. That was his second step of the plan. The last one was simple, it was just to wait.

* * *

Once she explains the plan to Castle, it was time to begin to do her job.

The first part was easy, distract the guards. The only thing she had to do was to scream. After all, they always enjoy a good show, and what most girls and _clients_ don't know is that every single one of those rooms has a viewing window and a hidden camera.

"Sick bastards!" was the only thought that run tough her head.

The second step was to lock all the doors. It has taken some time for her to find out how to do it, and she wasn't proud of all the things she did to get that knowledge, but what's done it's done, and there nothing she can do abut it now.

Once she locked the girls and the guards in theirs respective rooms, came the last part: She had to go after The Boss.

The Boss was an older man and he has been in this business since a very young age. He has always loved what he does, so he was never far away from his office. He was the one in charge of choosing the girls and his office was the only forbidden room in the whole complex building, unless you had a special invitation.

According to her original plan it wasn't the right time, but she had to act before they realized who she _really_ was or why Castle had been there. She knew where he was going to be, so it was her only chance to act.

"Well I guess plans change" she thought "here goes nothing!"

She walked trough the secret passage to get to his office. She knew it was there because of how she got her _job_, but she was the only one who knew where it was. That secret was a security blanket for The Boss, but he didn't have an idea of what her intentions were. The Boss accepted her because of her connections and the power that her name had in NY's underworld, but that she wasn't who everyone thought.

"I can believe this it's what my life has become!" she thought every time she began a new assignment just because of the power of her name.

Once she got to the door of the office, she walked right in and sat in the couch that was there. Thankfully, The Boss was to preoccupied with getting new girls to know what was happening in the 'operation center', as he liked to call it.

She could tell he knew she was there, but he wasn't going to pay attention to her, at least not until he felt he had make his position well known just by ignoring her, but she didn't mind she could wait. When he felt he had managed the small fee, he turned his head in her direction.

"It's there a reason for you been here?"

"Do I need one?" She smartly answers, with a cocky look on her face.

"Well, that depends, are you going to be doing things for me or _to_ me?" What the only respond she got.

She felt her skin crawled but she couldn't show how sick that question made her feel. This was all a part of the plan, it was the only way to get him out of the office. She _has_ to do it.

"I guess could do thing _to _you, but I don't think this is the best place for the things that I'm planning _with and for_ you" she said in a purr.

She could almost feel his excitement poring out of him, and she knew she had him right where he wanted him to be. So far, thing were going as they should be. This was the perfect time to strike.

* * *

They have been waiting for a while, but none of them really know what they were waiting for. Castle hadn't been able to explain, because he only knew he was waiting for this girl but not exactly what was going to happen and how she was going to get their suspect.

The boys knew that it was going to be something important and were almost sure that this _Boss_, as Castle said the girl called him, was the murder of the case they were working on.

But what was most socking of it all was Beckett behavior, she was acting suspicious while pacing the van from end to end, and they didn't know why. She knew more than what she letting on. She was scared but the boys couldn't see that they could only guess she was been impatient and didn't trust this girl to do the job.

But Castle could read her like an open book. So he could tell there was something else going on, he just couldn't pinpoint what it was that was off with Beckett's behavior, nor how she was _really_ feeling but he knew it wasn't just the time that it was taking this girl to get to them what was affecting her.

"She knows something more" he thought to himself "Please hurry up, I need to know, what it's going on!"

Suddenly he remembered that she had used a code when talking into the mic. He got closer to the boys and asked whispering

"Did you guys hear what the girl said to the mic?" Once the boys nodded he keep on talking "Do you know what it meant?"

"No bro, no clue!" Espo said, as Ryan shook his head at the same time. They really were connected by their partnership.

They didn't realize that Beckett had stop her pacing with in the van and was paying attention to what they were saying.

"They're the names of Broadway's musicals" she said.

All the sudden three pair if eyes were on her. Castle recovered first "Yeah, I know that, but what do those tittles mean?" He couldn't help asking.

"It means... they are... it just means that..." she began stuttering "they are just important, ok?" She finished getting work up at the end.

Once she stopped talking she began pacing again. They could hear her mumbling to herself but they couldn't make sense of the words she was saying. They wanted to keep asking her what she meant or how she knows this code, but she was lost in her brain and they weren't going to be getting an answer out of her.

"We would have to wait for this girl to show up, in order to get some answers" whispered Ryan. Both Castle and Espo nodded at his words.

And so they did, they waited and they saw Kate pace It worried them to see her so work up, but they couldn't do anything about it at the moment, because didn't know what the problem was.

All the sudden Beckett stopped pacing. "Do you guys hear that?" She asked.

They didn't know what she was talking about and it showed on their faces because she immediately said "I hear voices and a loud laugh, do you hear it now?". They did and she noticed that, she continues talking "Did she say what was going to be her signal for us Castle?"

He was going of answer but she was already opening the back door of the van and telling them all "It doesn't matter, I'm going out there anyway"

"Kate, no don't do it!" He said a little bit scared. He didn't know why, but he was sure it was going to ruin the plan. But she didn't care what he was saying, she was closing the door by the time he finished speaking.

He ran after her, but no for long, because she had stop at soon as she got out of the van. She was paralyzed and she couldn't stop staring at the couple that was just getting into the parking lot and walking across from where they were standing.

Once Castle followed her line of sight he realized that the girl they were waiting for was a part of this couple. It was almost finished. He could get his answers soon.

All the sudden he saw that the guy that was with her, Castle supposed he was the so called Boss, noticed them. Before any one the other three could respond, The Boss had already turned around and slapped the girl.

"You bitch! You called the cops on me? You're going to sell me out?" He screamed.

Before either Castle or Beckett could react, and faster that any of them thought possible the girl had The Boss in a dead lock and was taking him straight towards the van. But this tug wasn't going down without a fight.

In that moment the boys got out of the van with the intention of going after this lowlife, but before anyone of detectives could get any closer to the couple, the girl threw an unconscious Boss to the ground at their feet. They were all speechless.

"Do you guys think you could lend me some cuffs?" She sweetly asked while she sat on the unconscious body on the floor.

Castle didn't know who, but one of the boys threw his cuffs to this girl. When she finished securing the suspect she got up and walked straight to Beckett. The boys all look to each other, but none of them understood what was happening. They were thinking about every possible scenario where this two women could have met in the past but all the sudden it didn't matter, because those inner musings where interrupted by the new member of their group as she began to speak. All of the attention of the small group of police officers and tag along writers was on what she was gong to say.

"Hi Kay, long time no seen!" Was all it came out of her mouth, they next thing they heard was a gasp but it didn't came from the girl but from Kate, and before anyone of them could react Beckett was falling head first to the ground.

* * *

**AN: **As you can tell there's something that only Beckett knows about this new character, but what could it be? Please review to let me know if you want to know. Also if I made any misstake, I gladly apologized, and please let me know what they were. This story is un-beta, so all the grammatical errors are mine.


	3. Introducing

**AN: **Perdon I know it's been a while but RL and college are killing me. Now I know there's not many people following this story but it now became a personal challenge so you guys are going to be getting updates. New Challenge= To finish this fic. Wish me Luck. La voy a necesitar...

19-04-13

**Friendly Remainder:** Castle is not mine. I am from a spanish speacking country. Any and all mistakes are mine, and mine alone.

Now on with the show.

* * *

**Chapter 2: Introducing…**

Everything was black, she could hear noises in the distance, they were people talking but she couldn't understand what was been said.

_"I'm dreaming"_ she thought, _"This_ has _to be a dream! I_ have _to wake up! Come on Kate open your eyes!"_

She still couldn't open her eyes, but she notices that the voices were growing louder. She couldn't understand what was been said, but she knew those voices...

* * *

Before Beckett's body could hit the ground, the girl had her arms around Kate and was holding her up. When Castle saw Beckett collapse, he run until he had Kate in his arms, and then he lowered her to the ground. "Kate" he cried "Kate, come on! Wake up!"

"Don't make such a fuss, she just fainted. It's not that big of a deal" said the girl with an annoyed tone of voice.

This piss off the others two detectives, who decided to take a stand between this noisy girl and their 'Mom' and 'Dad'.

"What did you do to her?" Asked a mad Espo.

"Guys, you saw me, I jus said hi!" said the girl with an innocent smile on her face. But even they could see the mischievous glint in her eyes.

"That right" said a calmer, but still mad Ryan "the real question is, _who are you?_"

Castle wasn't _really_ paying attention to them, but he still wanted to know the answer to that question.

All the boys, Castle included, were waiting with beaded breath, for what this girl was going to say, how she was going to explain to them what was going on. But she ignored her questions and decided to change the subject.

"Don't you think that you should call for backup to come and pick him up" she said while pointing to the cuffed body on the floor.

The boys realized that she was right and although they didn't want to leave Beckett while she still hasn't woken up, but they had work to do and they knew that Castle wouldn't let anything happen to their boss and sister. So they went inside the van to make the calls.

Once the boys went away, the girl walked to Castel and Beckett. She kneeled next to Castle at Kate's side. "May I?" She asked Castle, in a softer voice that what he had heard come of her so far, while pointing at Beckett.

At hearing her talk, he stopped his chanting of 'Kate' and looked amaze to her face, he was trying to read her, and he didn't understand this girl or all the changes that she could make or what it was that she wanted with Beckett. But he noticed that she didn't mean anything bad for Beckett, he let her get closer, while he watched her in awe.

* * *

_She knew those voices._

She could hear a male voice saying her name like it was a mantra. She realize who that voice belong to, it was Castle. She really wanted to open her eyes, in order to see those beautiful blue eyes, but she couldn't. She wanted to wake up for him, but her body wasn't reacting to her wishes.

All the sudden she hear a second voice, she only said two words, but he could recognized that voice anywhere, that was a voice she thought she would never hear again. She remember years of hearing this soft tone and years of yearning to hear it again, years of wandering what happen to it and if this voice could still sing with a warm melodic tune like in her memories. _"So much time has passed"_ she thought.  
This new, old voice was talking to her, she needed to pay attention.

"Come on K, this boy is going to have a heart attack; you need to open you eyes!" Said that well known, soothing voice.

She felt a finger running trough her face in order to wake her up. This was the way her mom always acted when Kate refused to wake up in the morning. That mom gesture was enough to get to open her eyes. And just like many years ago it had the same effect now.

Kate couldn't believe what she was seeing. She would know that face anywhere. Nothing had change since that last time, yet everything was completely different. This girl was not the one that she remembers; she looked older, more grown up even than what her real age was. Beckett could see that life hadn't been easy for the other woman, because this wasn't a girl this was a woman. But not everything was different, no. Those eyes still remain the same, they were a little colder now but Kate still could make out the little girl that she once knew. She still lives in those eyes.

Beckett sat up, without taking her eyes off the other woman eyes. Just when she was beginning to open her mouth to talk, cruisers got speeding to the scene, and sirens, that she hadn't heard before grew louder that she thought possible. It was in that moment that Kate took notice to what had happened to her, and realized the position she was in. She stood up as quick as she could, it only took a moment, but al the sudden Kate was gone and detective Beckett to her place.

_"It's time to act as a detective."_ She thought looking at her companions, and she could almost swear she saw a proud look on the other woman face. But it was gone as soon as it appeared, only to be replaced with a neutral mask.

* * *

When the first cruises came to the scene, the boys walked to their boss and the five of them form a little group beside their suspect. Soon the new cops on the scene began to walk out of their cars and in the direction of the complex in order to process it. This cops weren't people from the 12th because the area wasn't theirs. It was the vice crew from the 27th.

Only one of the new arrivals was walking to them, and it wasn't an uniform like most of the others. When the detective was close enough to the group Beckett took a step in his direction to demonstrate that she was the one in charge and that he should talk to her, but, to her surprised and that of her boys, he pass them and almost run straight to the girl, tackling her in a bear hug.

"Wow girl! Is so good to see you out of this place!' said the detective.

"Wow, you're defiantly going soft! One would think that the big guy really cares about me! Are you going to cry, too? Or is it just the touchy feely kind of soft?" She teasingly asked, as she pulled out of the hug.

"Shut it, Gonzales! I'm just glad you're out so I don't have to go into that place again." He answers with a mischievous glint.

"Don't act like you didn't love to pull the chain of those guards." To this the only answer was a big belly laugh that had the girl laughing along the new detective.

Beckett and her team were in awe of this interaction they were seeing. They didn't understand anything. Gonzales noticed this and took pity of them.

"Ok, I think introductions are in order" she said looking between Beckett and this new detective. "I guess the best place to begin its whit myself. My name is Emma, Emma Gonzales" when the words were out of her mouth she heard a gasp, but this didn't deter her, so she continue talking. "And this is my partner Detective Donald Smith. We are vice, and have been working undercover in this place for months! You guys almost ruined _our_ plan, by the way."

"Girl, be nice!" Her partner chided her. "It's nice to meet you!" He said to the others detectives with a charming smile.

They didn't know what to do or what to say, so Emma saw it to herself to continue with the introductions.

"Well big guy, this is detective Kate Beckett, homicide from the 12th." She introduce while pointing to them "Her partner, writer Richard Castle. And the rest of her team, are detectives Ryan and Esposito. I'm assuming that the one in the vest is Ryan, and the latino one is Esposito. Am I right?" She asked in a cocky way.

The boys didn't know how she knew every single one of them. But Beckett's reaction made even less sense, she seamed kind of… happy? What about all the things that are happening is making Beckett smile like that? Today was a really estrange day.

When Emma finished talking, Kate didn't know what to do. This girl was the same, but nothing was as it should be. All the sudden she realized that she had a fan, in way. Emma had been following her work, that was the reason why she knew the names team. She was keeping tabs on her. Kate didn't know why but the thought made her feel happy and sure of herself.

All the boys looked at Beckett liked she had gone mad.

Emma understood what was going on in her head, so she chuckled to herself. "Beckett!" She said in a strong voice to get her attention "I think that we should have a chat. Would you mind coming to the precinct with us?" She asked nicely although every one of them knew it wasn't a question. It was more likely an order.

Beckett thanked Emma with her eyes. This gave her the perfect chance to get her detective mode fully on. She cleared her throat. "Right" she said "we would see you guys in the 27th"

Both groups began walking to theirs respective cars. But Kate couldn't move. She needed to talk to Emma; she had to find way, because she couldn't let the chance pass her by. When the boys were a few meters back she decided try.

"Emma!" She called. The other woman turned around at the sound of her name. Kate couldn't believe what she was seeing, this was the little girl that she hasn't seen in over a decade, she couldn't believe how grown up she look when she turn around, or the fact that she was a detective now.

_"Times really do change everything."_ Kate thought to herself. She couldn't get her voice out. She was having difficult thinking let alone speaking. Making and effort she found her voice.

"Em, what happen to you?" It wasn't more than a whisper but she knew that the other woman had heard her.

"I don't think you really want to know K!" She answered just as quietly "I don't blame you..." she began, but cut herself of, this wasn't the time or place to have this conversation "It really is nice to see you again!" She said with tone that let no room to argue. But Kate didn't listen.

"I never thought I'll see you again!" Kate thought out loud.

"I, on the other hand, always knew this day would come" was the respond she got. "It's good to see you Katie!" Was the last thing Emma said before she turned around and got in her car.

Beckett stood there until the car was out of sight. Things just had gotten more interesting

* * *

**AN: **What do you guys think so far? Do you know who this new gril is? What's her relationship with Beckett? How is it going to affect everything? What is it that you need to know?


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